| Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
| ObjectCache |
|
| 1.0;1 |
| 1 | package org.apache.ojb.broker.cache; | |
| 2 | ||
| 3 | /* Copyright 2002-2005 The Apache Software Foundation | |
| 4 | * | |
| 5 | * Licensed under the Apache License, Version 2.0 (the "License"); | |
| 6 | * you may not use this file except in compliance with the License. | |
| 7 | * You may obtain a copy of the License at | |
| 8 | * | |
| 9 | * http://www.apache.org/licenses/LICENSE-2.0 | |
| 10 | * | |
| 11 | * Unless required by applicable law or agreed to in writing, software | |
| 12 | * distributed under the License is distributed on an "AS IS" BASIS, | |
| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
| 14 | * See the License for the specific language governing permissions and | |
| 15 | * limitations under the License. | |
| 16 | */ | |
| 17 | ||
| 18 | import org.apache.ojb.broker.Identity; | |
| 19 | ||
| 20 | /** | |
| 21 | * The <code>ObjectCache</code> stores all Objects loaded by the | |
| 22 | * {@link org.apache.ojb.broker.PersistenceBroker} from a DB. | |
| 23 | * When the PersistenceBroker tries to get an Object by its Primary key values | |
| 24 | * it first lookups the cache if the object has been already loaded and cached. | |
| 25 | * <br/><br/> | |
| 26 | * Using an ObjectCache has several advantages: | |
| 27 | * - it increases performance as it reduces DB lookups. | |
| 28 | * - it allows to perform circular lookups (as by crossreferenced objects) | |
| 29 | * that would result in non-terminating loops without such a cache. This will be internally handled by OJB, no | |
| 30 | * need to take care of this. | |
| 31 | * - it maintains the uniqueness of objects as any Db row will be mapped to | |
| 32 | * exactly one object. | |
| 33 | * <br/><br/> | |
| 34 | * This interface allows to have userdefined Cache implementations. | |
| 35 | * The ObjectCacheFactory is responsible for generating cache instances. | |
| 36 | * by default it uses the OJB {@link ObjectCacheDefaultImpl}. | |
| 37 | * <br/><br/> | |
| 38 | * <b>Note:</b> Each {@link org.apache.ojb.broker.PersistenceBroker} was | |
| 39 | * associated with its own <code>ObjectCache</code> instance at creation | |
| 40 | * time. | |
| 41 | * <br/> | |
| 42 | * {@link ObjectCacheFactory} is responsible for creating <code>ObjectCache</code> | |
| 43 | * instances. To make the <code>ObjectCache</code> implementation work, a | |
| 44 | * constructor with {@link org.apache.ojb.broker.PersistenceBroker} and | |
| 45 | * {@link java.util.Properties} as arguments or only <code>PersistenceBroker</code> | |
| 46 | * argument is needed. | |
| 47 | * | |
| 48 | * @author <a href="mailto:thma@apache.org">Thomas Mahler<a> | |
| 49 | * @author <a href="mailto:armin@codeaulait.de">Armin Waibel<a> | |
| 50 | * | |
| 51 | * @version $Id: ObjectCache.java,v 1.1 2007-08-24 22:17:29 ewestfal Exp $ | |
| 52 | */ | |
| 53 | public interface ObjectCache | |
| 54 | { | |
| 55 | /** | |
| 56 | * Used to cache objects by it's {@link org.apache.ojb.broker.Identity}. | |
| 57 | * | |
| 58 | * @param oid Identity of the object to cache. | |
| 59 | * @param obj The object to cache. | |
| 60 | */ | |
| 61 | public void cache(Identity oid, Object obj); | |
| 62 | ||
| 63 | /** | |
| 64 | * Lookup object with Identity 'oid' in cache. | |
| 65 | * | |
| 66 | * @param oid Identity of the object to search for. | |
| 67 | * @return The cached object or <em>null</em> if no matching object for | |
| 68 | * specified {@link org.apache.ojb.broker.Identity} is found. | |
| 69 | */ | |
| 70 | public Object lookup(Identity oid); | |
| 71 | ||
| 72 | /** | |
| 73 | * Removes an Object from the cache. | |
| 74 | * | |
| 75 | * @param oid Identity of the object to be removed. | |
| 76 | */ | |
| 77 | public void remove(Identity oid); | |
| 78 | ||
| 79 | /** | |
| 80 | * Clear the cache. | |
| 81 | */ | |
| 82 | public void clear(); | |
| 83 | } |